Electrochromic recording per se is well known in the art. It is, for example, thoroughly discussed in U.S. Pat. No. 4,211,616 where operations of typical electrochromic systems are explained.
In U.S. patent application Ser. No. 426,478, now U.S. Pat. No. 4,439,280 the use of certain phenothiazine leucodyes is disclosed.
Japanese Pat. No. 73 52,778, abstracted in Chemical Abstracts Vol. 79, page 386, 1973, at page 137166, shows certain phenoxazine derivatives.
No prior art of which we are aware, however, discloses the use of the phenazine compounds of the present invention in electrochromic recording.